diff --git a/spec/index.html b/spec/index.html
index a68feeefe..ad1549cf1 100644
--- a/spec/index.html
+++ b/spec/index.html
@@ -19,6 +19,7 @@
 	<script type="text/javascript" src="../src/MarkerClusterGroup.js"></script>
 	<script type="text/javascript" src="../src/MarkerCluster.QuickHull.js"></script>
 	<script type="text/javascript" src="../src/MarkerCluster.Spiderfier.js"></script>
+	<script type="text/javascript" src="../src/MarkerOpacity.js"></script>
 
 	<script>
 		mocha.setup('bdd');
@@ -56,6 +57,8 @@
 	<script type="text/javascript" src="suites/spiderfySpec.js"></script>
 	<script type="text/javascript" src="suites/zoomAnimationSpec.js"></script>
 
+	<script type="text/javascript" src="suites/RememberOpacity.js"></script>
+
 	<script>
 		(window.mochaPhantomJS || window.mocha).run();
 	</script>
diff --git a/spec/suites/RememberOpacity.js b/spec/suites/RememberOpacity.js
new file mode 100644
index 000000000..bb023a59f
--- /dev/null
+++ b/spec/suites/RememberOpacity.js
@@ -0,0 +1,151 @@
+describe('Remember opacity', function () {
+	var map, div, clock, markers;
+
+	var markerDefs = [
+		{latLng: [ 0, 0], opts: {opacity: 0.9}},
+		{latLng: [ 0, 1], opts: {opacity: 0.5}},
+		{latLng: [ 0,-1], opts: {opacity: 0.5}},
+		{latLng: [ 1, 0], opts: {opacity: 0.5}},
+		{latLng: [-1, 0], opts: {opacity: 0.5}},
+		{latLng: [ 1, 1], opts: {opacity: 0.2}},
+		{latLng: [ 1,-1], opts: {opacity: 0.2}},
+		{latLng: [-1, 1], opts: {opacity: 0.2}},
+		{latLng: [-1,-1], opts: {opacity: 0.2}}
+	];
+
+	var bounds = L.latLngBounds( L.latLng( -1.1, -1.1),
+	                             L.latLng(  1.1,  1.1) );
+
+	beforeEach(function () {
+		clock = sinon.useFakeTimers();
+
+		div = document.createElement('div');
+		div.style.width = '200px';
+		div.style.height = '200px';
+		document.body.appendChild(div);
+
+		map = L.map(div, { maxZoom: 18 });
+
+		markers = [];
+		for (var i=0; i<markerDefs.length; i++) {
+			markers.push( L.marker(markerDefs[i].latLng, markerDefs[i].opts ) );
+		}
+	});
+	afterEach(function () {
+		clock.restore();
+
+		document.body.removeChild(div);
+	});
+
+	it('clusters semitransparent markers into an opaque one', function () {
+		map.setView(new L.LatLng(0,0), 1);
+
+		var clusterLayer = new L.MarkerClusterGroup({
+			maxClusterRadius: 20
+		});
+		clusterLayer.addLayers(markers);
+		map.addLayer(clusterLayer);
+
+		var visibleClusters = clusterLayer._featureGroup.getLayers();
+		expect(visibleClusters.length).to.be(1);
+		expect(visibleClusters[0].options.opacity).to.be(1);
+	});
+
+
+	it('unclusters an opaque marker into semitransparent ones', function () {
+		map.setView(new L.LatLng(0,0), 1);
+		var visibleClusters;
+
+		var clusterLayer = new L.MarkerClusterGroup({
+			maxClusterRadius: 20
+		});
+		clusterLayer.addLayers(markers);
+		map.addLayer(clusterLayer);
+
+		map.fitBounds(bounds);
+		clock.tick(1000);
+
+		visibleClusters = clusterLayer._featureGroup.getLayers();
+		expect(visibleClusters.length).to.be(9);
+		for (var i=0; i<9; i++) {
+			expect(visibleClusters[i].options.opacity).to.be.within(0.2,0.9);
+		}
+
+		// It shall also work after zooming in/out a second time.
+		map.setView(new L.LatLng(0,0), 1);
+		clock.tick(1000);
+
+		map.fitBounds(bounds);
+		clock.tick(1000);
+
+		visibleClusters = clusterLayer._featureGroup.getLayers();
+		expect(visibleClusters.length).to.be(9);
+		for (var i=0; i<9; i++) {
+			expect(visibleClusters[i].options.opacity).to.be.within(0.2,0.9);
+		}
+	});
+
+
+	it('has no problems zooming in and out several times', function () {
+		var visibleClusters;
+
+		var clusterLayer = new L.MarkerClusterGroup({
+			maxClusterRadius: 20
+		});
+		clusterLayer.addLayers(markers);
+		map.addLayer(clusterLayer);
+
+		// Zoom in and out a couple times
+		for (var i=0; i<10; i++) {
+			map.fitBounds(bounds);
+			clock.tick(1000);
+
+			visibleClusters = clusterLayer._featureGroup.getLayers();
+			expect(visibleClusters.length).to.be(9);
+			for (var i=0; i<9; i++) {
+				expect(visibleClusters[i].options.opacity).to.be.within(0.2,0.9);
+			}
+
+			map.setView(new L.LatLng(0,0), 1);
+			clock.tick(1000);
+
+			visibleClusters = clusterLayer._featureGroup.getLayers();
+			expect(visibleClusters.length).to.be(1);
+			expect(visibleClusters[0].options.opacity).to.be(1);
+		}
+
+	});
+
+	it('retains the opacity of each individual marker', function () {
+		map.setView(new L.LatLng(0,0), 1);
+
+		var visibleClusters;
+		var clusterLayer = new L.MarkerClusterGroup({
+			maxClusterRadius: 20
+		});
+		clusterLayer.addLayers(markers);
+		map.addLayer(clusterLayer);
+
+
+		// Zoom in and out a couple times
+		for (var i=0; i<5; i++) {
+			map.fitBounds(bounds);
+			clock.tick(1000);
+
+			map.setView(new L.LatLng(0,0), 1);
+			clock.tick(1000);
+		}
+
+		for (var i=0; i<markerDefs.length; i++) {
+
+// 			console.log(markerDefs[i].latLng, markerDefs[i].opts.opacity);
+
+			map.setView(L.latLng(markerDefs[i].latLng), 18);
+			clock.tick(1000);
+			visibleClusters = clusterLayer._featureGroup.getLayers();
+			expect(visibleClusters.length).to.be(1);
+			expect(visibleClusters[0].options.opacity).to.be(markerDefs[i].opts.opacity);
+		}
+	});
+
+});
\ No newline at end of file